1. Field
The present invention relates to an interspinous process spacer implant for being implanted between spinous processes of neighboring vertebrae.
2. Discussion of Prior Art
Spinal traumata or diseases can lead to spine conditions in which the relative positions of neighboring vertebrae are such that a person experiences pain. For treating such conditions spacer implants are positioned between the spinous processes of the neighboring vertebrae to prevent from relative motion between the two vertebrae. Typical implants are, for example, disclosed in U.S. Pat. No. 8,246,655 B2 and EP 2 117 470 B1 and WO 2013/109363 A1.
EP 2 117 470 B1 describes an intervertebral implant with a first body and a second body which are hinged together by means of an off-center hinge. The first body includes an upper bearing surface for contacting an upper spinous process which bearing surface is located between two upper projections extending from the first body. Likewise, the second body includes a lower bearing surface for contacting a lower spinous process which bearing surface is located between two lower projections extending from the first body. The first and second bodies also include contact surfaces where the bearing surfaces and the contact surfaces are located at opposite ends of the respective body. The first and second bodies can be rotated about the hinge until the contact surfaces come into contact. The bodies are then fixed in this configuration by an arresting mechanism.
WO 2013/109363 A1 describes an intervertebral implant with a first body and a second body which are hinged together by means of a central hinge. A first body includes a first upper surface and a first lower surface, where a first upper projection and a first lower projection extend from the first upper surface and the first lower surface, respectively. A second body includes a second upper surface and a second lower surface where a second upper projection and a second lower projection extend from the second upper surface and the second lower surface, respectively. The first lower surface is provided with a plurality of ribs which can cooperate with a screw which can be screwed through a threated a through hole in the second lower projection. When the screw is screwed through the through hole the tip of the screw reaches the ribs and thereby secures the first and second bodies relative to each other against rotation about the hinge at a desired distance between the first and second upper projections.
Sometimes it is not sufficient to fix neighboring vertebrae relative to each other. In these cases it might be necessary to enlarge the space between neighboring vertebrae in order to release pressure from spinal nerve routes. Intervertebral implants which allows for distracting neighboring vertebrae are, for example, disclosed in US 2011/0118788 A1, US 2012/0277796 A1 and and WO 2013/0277796 A1. The intervertebral implants disclosed in these documents allow for distracting vertebrae by expanding the implant. Once the desired distracting is achieved the implants are fixed in their expanded configuration by means of screws.